PROJECT SUMMARY Quality of language input plays an instrumental role in children?s language development. One qualitative feature of linguistic input that may impact language development is whether the input is provided by a native or a non-native speaker. However, while aspects of non-native input (e.g., foreign accent) have been shown to interfere with language processing, little is known about the impact of non-native input on children?s learning. Because bilingual children have an increased likelihood of receiving linguistic input from non-native speakers, it is possible that non-native input influences learning differently in bilingual children than in monolingual children. Furthermore, children with language impairment may be particularly vulnerable to the effects of non-native input because of documented processing difficulties. Therefore, the goal of the proposed research is to assess how children with different language backgrounds (i.e., monolingual vs. bilingual) and children with distinct language abilities (i.e., with typical vs. impaired language skills) learn novel words from native vs. accented speakers. A total of 40 monolingual English-speaking children and 40 bilingual Spanish-English speaking children between the ages of 4 and 5 will participate. Within each group, half of the children will be typically-developing, and half of the children will be identified as being at risk for language impairment. Under Specific Aim 1, we will examine the impact of accented speech on word learning in monolingual and bilingual typically developing children. We will present words under three conditions: native American-English accent, Spanish-accented English, and Korean-accented English. These three accents will be employed to assess the interaction between previous experience with accented speech and word learning outcomes. We hypothesize that all children will experience difficulties when learning words in the accented conditions; however, experience with Spanish-accented English may facilitate learning in the Spanish-accented English condition for the bilingual children. The findings will reveal whether accented input poses risks for word learning in typical development and whether accent familiarity may mediate learning. Under Specific Aim 2, we will examine the impact of accented speech on word learning in bilingual and monolingual children who are at risk for language impairment. The findings will reveal whether accented input poses particular challenges to word learning in children with language impairment or who are at risk for language impairment. The findings will have significant theoretical and clinical consequences. Theoretically, the proposed project will reveal whether processing deficits documented in children with language impairment make children who are at risk for language impairment more vulnerable to the effects of accent. Clinically, the proposed project will inform public-health concerns associated with documenting environmental risk-factors for children?s language development.